Exhaust gases deriving from the production cycle in the detergent industry always contain quite considerable amounts of powder, which, if they are not captured in advance, escape to atmosphere together with the discharge gases, causing unacceptable levels of pollution. Although the main problem is to eliminate atmospheric pollution, the economic advantages deriving from the recovery of products which, once captured and collected in the form of aqueous solutions or suspensions (the method will be explained below), may be recycled, are also to be taken into account. In this way only the stream of purified gas is discharged from the system. The method with which the present invention is concerned is of the wet type because it is not advantageous, given the concentration and the fineness of the powder contained in the exhaust gases, to use a dry method.
A wet method is also preferable as a result of the fact that the exhaust gases may contain, in addition to detergent powders, organic products distilled during a spray drying stage, good extraction results being obtained for these products with the use of wet systems.